This invention relates generally to a mounting device for electrically connecting an electronic part and each of its terminals to a substrate board for testing.
Often, integrated circuit (IC) chips which are sealed in resin after their manufacture are subjected to a reliability testing called a burn-in test and/or an electric properties test prior to their shipment to distinguish between satisfactory product and unsatisfactory product.
Such an electric properties test, tests the input and output characteristics of the IC chips, pulse characteristics and noise leeway, etc. In the burn-in test, IC packages are arranged in an oven and then functionally tested for a selected period of time at an elevated temperature and voltage level (e.g., 125xc2x0 C. at 120% of normal voltage level). Only those that pass these tests are shipped out as satisfactory products.
One common package in use today is a BGA (Ball Grid Array) package with connective terminals made up of globular solder balls arranged in a matrix or zigzag fashion on the underside of the package. The advantages of this BGA package design exists in having wider connective terminal pitches while the outside dimensions are small and the connective terminals are strong.
FIGS. 7(a) and 7(b) show a prior art socket for the burn-in test built for mounting a BGA package. The socket 101 has a square-shaped base 102 made of a plastic resin or the like, on which a slider member 103 is arranged in such a manner as to freely slide back and forth in the horizontal direction during the mounting of BGA package 100.
Above base 102, an attached cover 104 with an opening 104a is constructed so as to move up and down as compared with base 102 by the means of compressive coil springs 105. Slider 103 and base 102 are configured with through holes (not shown in the drawing) that correspond to each solder ball 100a of the BGA package. A plurality of contacts 106 are mounted in base 102 for compressively making electrical contact with the solder balls 100a of the BGA package with each contact 106 extending through the through hole of base 102 and slider 103. Each contact 106 has a centered body portion made of metal with a pair of metallic arms 106a and 106b provided at one tip thereof.
On both sides of slider 103, a slide mechanism is provided for moving the slider 103 in parallel with the bottom of base 102. The slide mechanism includes first L-shaped lever members 108 freely rotatably installed at both ends of a shaft 107 that is positioned on one edge (right-side edge in the drawings) of base 102 with a short arm portion 108a of lever member 108 freely rotatably linked to a shaft 109 positioned vertically below shaft 107 that touches slider 103.
Second lever members 111 are installed freely rotatably at both ends of a shaft 110 that are positioned on the other edge side of base 102 from shaft 107. At the middle of each second lever member 111, the tip of first lever member 108 is fixed in a freely swinging manner by means of a pin 112.
When the cover 104 is in the up position FIG. 7(a), the tip part 111a of second lever member 111 is so arranged as to touch a protuberant part 104b of cover 104. In the vicinity of shaft 110, a compressive coil spring 113 is provided in base 102 for the purpose of biasing slider 103 toward one preferred at rest position.
In a socket 101 described above, when cover 104 is pressed down from a state shown in FIG. 7(a) to a state shown in FIG. 7(b), first and second lever members 108 and 111 rotate toward base 102 and, along with the movement of lever members 108, shaft 109 engages slider 103, thereby moving it in the X-direction. As a result of this movement of slider 103, one arm 106a of contact 106 moves away from arm 106b to an open position. In this state, BGA package 100 can be placed on an adaptor 103c of slider 103 with each solder ball 100a of BGA package 100 positioned between arms 106a and 106b. When the pressure on the cover is released, first and second lever members 108 and 111 rise and the slider 103 is restored toward its original position by the force of compressive coil spring 113 with the consequence that the arms 106a and 106b are closed and each solder ball 100a of BGA package 100 is held by the arms of each contact. In such position, each solder ball 100a of package 100 and each contact 106 are electrically connected.
This socket has proved to be useful in the operation but has a large number of parts with a somewhat complex construction. It requires the movement of linking mechanisms 108, 111 and slider 103 to cause the opening and closing of arms 106a, 106b in a set sequence of operations. Moreover, socket 101 tends to be large and heavy compared to other sockets with the various moving parts subject to wear in the case of the resin slider causing wear particles in the socket.
Still further, wear between moving parts (actuator and slider) can cause powder particles which can cause failure of electronic package mounting device. Also, there can be a problem with uniformly maintaining proper contact opening distance when there is bending of the wiring substrate.
An object of the present invention is the provision of a mounting device/system which overcomes the prior art limitations described above and which prevents concomitant trouble resulting from using a drive mechanism as the cover or lever, etc., to control the movement of the contact arms.
Another object of this invention lies in providing an electronic part mounting device using a contact opening and closing tool separate from the base member and where the friction to open and close the socket contacts is reduced to increase the interval between maintenance work and particularly suitable for an electronic part mounting device with a large number of contact members.
Yet another object of this invention lies in offering an electronic part mounting device where there is uniformity in the amount of opening of the arm-shaped contact parts.
Other objects, advantages and details of the novel and improved electronic part mounting device of the present invention appear in the following detailed description of the prepared embodiments of the invention.